The Homogeneity Analysis of Rainfall Time Series for Selected Meteorological Stations in Iraq

Abstract

In the present research, the homogeneity tests were conducted for 36 meteorological stations records throughout Iraq. For this purpose, monthly and annual total rainfall records at stations operated by Iraqi meteorological organization and seismology (IMOS) from 1981 to 2010 were considered. Four methods namely standard normal homogeneity test (SNHT), Buishand range test, Pettitt test, and von Neumann ratio tests were chosen to detect the inhomogeneity of the rainfall time series. The results of each of the testing methods were evaluated separately at a significance level of 95% and the inhomogeneous years have been determined. With the application of the four mentioned methods, inhomogeneity was detected at 30% of stations (11 stations) and 70 % of stations (25 stations) were found to be homogeneous. The results of the different tests are condensed into three classes: ‘useful’, ‘doubtful’ and ‘suspect’. A qualitative interpretation of this classification is given, 31 stations were assigned as useful, two stations were labeled as doubtful and three stations were assigned as suspect.